Seo SI, Park H, You SC, et al. - In this study, the relationship between proton pump inhibitors (PPIs) and gastric cancer in Korea was explored. Researchers examined the original and common data model versions of the Korean National Health Insurance Service database from 2002 to 2013. The incidence rates of gastric cancer were compared after 1-year drug exposure, between new users of PPIs and other drugs excluding PPIs, by Cox proportional hazards model. The incidence of gastric cancer was also examined among PPI users after H. pylori eradication. The study enrolled 11,741 patients in matched PPI and non-PPI cohorts after large-scale propensity score matching. It was shown that PPI use was correlated with gastric cancer, regardless of H. pylori eradication status. For gastric cancer, long-term PPIs should be used with caution in high-risk regions.